Polycarbonates are amorphous polymers valued for their optical properties, thermal resistance, toughness, and impact resistance. Copolyestercarbonates, having both ester and carbonate repeat units, are known to have polycarbonate-like properties together with substantially increased melt flow at the same molecular weight compared to an ordinary aromatic polycarbonate.
The trend in consumer electronics is to make entire devices lighter and thinner. New device designs provide new challenges to plastic composites as the designs require a plastic composite with an improved balance of melt flow and impact strength while substantially maintaining tensile strength and heat resistance. This property combination has been difficult to achieve with polycarbonate composites, due in part to the high melt viscosity of polycarbonate. Moreover, some applications including in-mold decoration/labeling (IMD/IML) require low processing temperatures to avoid ink wash-out, and high melt flow to fill a mold and adhere to a membrane within the mold. Polycarbonate composites need high process temperature to reach the flow requirement, but such temperatures cause ink wash-out problems.
There is a need for thermoplastic compositions having an improved balance of impact strength and melt flow while substantially retaining tensile properties and heat resistance.